Rear axle assemblies are well known and commonly used in a variety of vehicles including automobiles, trucks, all terrain vehicles and small utility vehicles. The assemblies typically include a differential housing and two laterally extending axle tubes secured at one end to the differential housing. Each of the axle tubes can be adjacent to a wheel at an opposite end. The differential housing contains the final gear set in the drivetrain used to transfer torque from the vehicle engine to the rear wheels and also contains lubrication oil.
The axle tubes typically include one or more mount structures that can be used to secure various components of the vehicle suspension system. The load path for suspension loads is typically from one axle tube to the differential housing and then to the other axle tube. It is desirable to precisely maintain the position of the axle tubes relative to the differential housing to maintain the position of the suspension system mounting locations on the axle tubes.
Various methods are known to prevent relative movement, such as relative rotation, between the axle tubes and the differential housing. The differential housing is typically made of cast iron or a stamped sheet metal fabrication. When made of cast iron, each axle tube can be press fit into a bore in the differential housing, with the press fit preventing relative movement between the axle tubes and the differential housing.
Other known methods of maintaining the position of the axle tubes relative to the differential housing include the use of lock pins disposed at a right angle to the axis of the respective axle tube and engaged with the axle tube and the differential housing. Plug welds can also be used to fix the axle tubes relative to the differential housing. In this case, if the differential housing is made of cast iron, the plug weld may not be intended to fuse the axle tubes to the differential housing since welding cast iron can be problematic. Instead, the plug welds can be located on the axle tubes and extend into a mating aperture in the differential housing.
Known axle assemblies also include fabricated assemblies where the axle tubes and differential housing are made out of substantially the same material and are welded together forming one large unit. Known all terrain vehicles and small utility vehicles can include a differential housing made of cast aluminum and steel axle tubes. Each axle tube can include a flange that allows the axle tube to be bolted to the differential housing.
While the various methods described previously have been advantageously utilized, they may not be suitable for certain applications depending upon considerations of the magnitude of expected suspension loads, material strengths and the costs associated with manufacturing and assembling the axle assembly.